float_1664qam24.m

stbc在2发2收

%  表示t2*r4系统,码率= 1;
% 16qam 64qam

clear
clc
snr_min=0;
snr_max=35;
stepsize = 2.5;
%-------------全局参量--------------------------------%
Mod_type = 4;           %qam调制有三种情况(2=4qam,4=16qam,6=64qam)
Ofdm_bits = 100;       %一个ofdm符号长度
Tx_num = 2;             %发送天线个数,这里仅仅是赋一个默认的初始值
Rx_num = 2;             %接收天线个数
Time_length = 2;        %进行正交编码的时隙长度,这里仅仅是赋一个默认的初始值(2 or 4)
Source_length = Tx_num*Ofdm_bits*Mod_type;  %信源输出码子个数(映射前)
pqam_length = Ofdm_bits*Mod_type;            %每根天线所需的码子个数(映射前)

sig_code = zeros(Tx_num,pqam_length);
sig_code = randint(Tx_num,pqam_length);

table16 = [1+j, 3+ j, 1+3j, 3+3j,...
        1-j, 1-3j, 3- j, 3-3j,...
        -1+j,-1+3j,-3+ j,-3+3j,...
        -1-j,-3- j,-1-3j,-3-3j];
table64 = [1+j, 3+ j, 1+3j, 3+3j, 7+1j, 5+ j, 7+3j, 5+3j, 1+7j, 3+7j, 1+5j, 3+5j, 7+7j, 5+7j, 7+5j, 5+5j,...
        1-j, 1-3j, 3- j, 3-3j, 1-7j, 1-5j, 3-7j, 3-5j, 7- j, 7-3j, 5- j, 5-3j, 7-7j, 7-5j, 5-7j, 5-5j,...
        -1+j,-1+3j,-3+ j,-3+3j,-1+7j,-1+5j,-3+7j,-3+5j,-7+ j,-7+3j,-5+ j,-5+3j,-7+7j,-7+5j,-5+7j,-5+5j,...
        -1-j,-3- j,-1-3j,-3-3j,-7- j,-5- j,-7-3j,-5-3j,-1-7j,-3-7j,-1-5j,-3-5j,-7-7j,-5-7j,-7-5j,-5-5j];
table16 = table16/sqrt(10);
table64 = table64/sqrt(42);
switch Mod_type
    case 4
        for i=1:Tx_num
            for n=1:Ofdm_bits
                table_index = sig_code(i,(n-1)*Mod_type+1)*8+sig_code(i,(n-1)*Mod_type+2)*4+...
                    sig_code(i,(n-1)*Mod_type+3)*2+sig_code(i,(n-1)*Mod_type+4);
                qam_code(i,n) = table16(table_index+1);
            end
        end
    case 6
        for i=1:Tx_num
            for n=1:Ofdm_bits
                table_index = sig_code(i,(n-1)*Mod_type+1)*32+sig_code(i,(n-1)*Mod_type+2)*16+...
                    sig_code(i,(n-1)*Mod_type+3)*8+sig_code(i,(n-1)*Mod_type+4)*4+...
                    sig_code(i,(n-1)*Mod_type+5)*2+sig_code(i,(n-1)*Mod_type+6);       
                qam_code(i,n) = table64(table_index+1);
            end
        end  
end

stbc_code = zeros(Time_length,Tx_num,Ofdm_bits);         %stbc 编码矩阵
for m=1:Tx_num            
    stbc_code(1,m,:) = qam_code(m,:); 
end
stbc_code(2,1,:) = -conj(qam_code(2,:));
stbc_code(2,2,:) = conj(qam_code(1,:)); 

ch_scale = sqrt(Tx_num);
stbc_code = stbc_code/ch_scale;

%-----------------------迭代开始 信噪比 由小到大------------------------%

iterative_length = 0;
for snr_db_step =snr_min:stepsize:snr_max    % 信噪比从snr_min--snr_max
    iterative_length = iterative_length+1
    %------------(省略CP头和训练序列)上信道,乘性噪声------------------------%
    
    rec_code = zeros(Time_length,Rx_num,Ofdm_bits);
    channel_mul_noice = zeros(Tx_num,Rx_num,Ofdm_bits);
    ch_mul_noice = sqrt(0.5)*(randn(Tx_num,Rx_num,Ofdm_bits)+j*randn(Tx_num,Rx_num,Ofdm_bits));
    for n = 1:Time_length 
        for m = 1:Ofdm_bits
            rec_code(n,:,m) = stbc_code(n,1:Tx_num,m)*ch_mul_noice(1:Tx_num,1:Rx_num,m);
        end
    end
    
    %---------------------信号功率统计,加高斯白噪声----------------------------%
    sig_pante_pow = 0;
    for n = 1:Rx_num
        Agwn = sqrt(10^(-snr_db_step/10)/2)*(randn(Time_length,1,Ofdm_bits)+j*randn(Time_length,1,Ofdm_bits));
        rec_code(:,n,:) = rec_code(:,n,:) + Agwn;      
    end
    
    rec_code = rec_code*ch_scale;
    
    %%%%%%%%%%%%%%%%%%%%%%%%%% 定点仿真 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
    %------------------------接收信号并进行stbc译码----------------------------%
    
    rec_code_r = real(rec_code);
    rec_code_i = imag(rec_code);
    ch_mul_noice_r = real(ch_mul_noice);
    ch_mul_noice_i = imag(ch_mul_noice);
    decode_out = zeros(Tx_num,Ofdm_bits);
    demap_int = zeros(Tx_num,Ofdm_bits);
    %rec_code = rec_code*qam_scale;
    %[decode_out,demap_int] = stbc_decode(rec_code,channel_mul_noice);
    compare_tempt = zeros(Time_length,2); 
    result_index = zeros(1,Time_length);
    if Mod_type == 4
        star_index_length = 16;
    end
    if Mod_type == 6
        star_index_length = 64;
    end
    for n = 1:Ofdm_bits
        decode_tempt = zeros(1,2);         % Time_length = 2
        decode_tempt_r = zeros(1,2);
        decode_tempt_i = zeros(1,2);
        m = reshape(ch_mul_noice(:,:,n),1,Tx_num*Rx_num);              % 8 = Tx_num*Rx_num=2*4
        ch_sum = norm(m)^2;
        for r =  1:Rx_num 
            %decode_tempt(1,1) = decode_tempt(1,1) + rec_code(1,r,n)*conj(ch_mul_noice(1,r,n))+ conj(rec_code(2,r,n))*ch_mul_noice(2,r,n);            
            mult_tempt1 = rec_code_r(1,r,n)*ch_mul_noice_r(1,r,n);
            mult_tempt2 = rec_code_i(1,r,n)*ch_mul_noice_i(1,r,n);
            mult_tempt3 = rec_code_r(2,r,n)*ch_mul_noice_r(2,r,n);
            mult_tempt4 = rec_code_i(2,r,n)*ch_mul_noice_i(2,r,n);
            decode_tempt_r(1,1) = decode_tempt_r(1,1)...
                +mult_tempt1 + mult_tempt2...
                +mult_tempt3 +mult_tempt4;
            mult_tempt1 = - rec_code_r(1,r,n)*ch_mul_noice_i(1,r,n);
            mult_tempt2 = rec_code_i(1,r,n)*ch_mul_noice_r(1,r,n);
            mult_tempt3 = rec_code_r(2,r,n)*ch_mul_noice_i(2,r,n);
            mult_tempt4 = - rec_code_i(2,r,n)*ch_mul_noice_r(2,r,n);
            decode_tempt_i(1,1) = decode_tempt_i(1,1)...
                +mult_tempt1+mult_tempt2 ...
                +mult_tempt3 +mult_tempt4;
            %decode_tempt(1,2) = decode_tempt(1,2) + rec_code(1,r,n)*conj(ch_mul_noice(2,r,n))- conj(rec_code(2,r,n))*ch_mul_noice(1,r,n); 
            mult_tempt1 = rec_code_r(1,r,n)*ch_mul_noice_r(2,r,n);
            mult_tempt2 = rec_code_i(1,r,n)*ch_mul_noice_i(2,r,n);
            mult_tempt3 = - rec_code_r(2,r,n)*ch_mul_noice_r(1,r,n);
            mult_tempt4 = - rec_code_i(2,r,n)*ch_mul_noice_i(1,r,n);
            decode_tempt_r(1,2) = decode_tempt_r(1,2)...
                +mult_tempt1 + mult_tempt2...
                +mult_tempt3+mult_tempt4;
            mult_tempt1 = -rec_code_r(1,r,n)*ch_mul_noice_i(2,r,n);
            mult_tempt2 = rec_code_i(1,r,n)*ch_mul_noice_r(2,r,n);
            mult_tempt3 = -rec_code_r(2,r,n)*ch_mul_noice_i(1,r,n);
            mult_tempt4 = rec_code_i(2,r,n)*ch_mul_noice_r(1,r,n);
            decode_tempt_i(1,2) = decode_tempt_i(1,2)...
                +mult_tempt1 + mult_tempt2...
                +mult_tempt3+ mult_tempt4;                
        end
        decode_tempt(1,1) = decode_tempt_r(1,1)+j*decode_tempt_i(1,1);
        decode_tempt(1,2) = decode_tempt_r(1,2)+j*decode_tempt_i(1,2);
        if Mod_type == 4
            for star_index = 1:star_index_length
                compare_tempt(1,1) = abs(decode_tempt(1,1)-table16(star_index))^2+...
                    (-1+ch_sum)*abs(table16(star_index))^2;
                compare_tempt(2,1) = abs(decode_tempt(1,2)-table16(star_index))^2+...
                    (-1+ch_sum)*abs(table16(star_index))^2;
                if star_index==1
                    compare_tempt(1,2) = compare_tempt(1,1);
                    compare_tempt(2,2) = compare_tempt(2,1); 
                    result_index(1) = star_index;
                    result_index(2) = star_index;
                else
                    if compare_tempt(1,1) < compare_tempt(1,2)
                        compare_tempt(1,2) = compare_tempt(1,1);
                        result_index(1) = star_index;
                    end
                    if compare_tempt(2,1) < compare_tempt(2,2)
                        compare_tempt(2,2) = compare_tempt(2,1);
                        result_index(2) = star_index;
                    end
                end
            end % star_index = 1:16
            decode_out(1,n) = table16(result_index(1));
            decode_out(2,n) = table16(result_index(2));
            demap_int(1,n) = result_index(1)-1;
            demap_int(2,n) = result_index(2)-1;
        end % Mod_type = 4
        if Mod_type == 6
            for star_index = 1:star_index_length
                compare_tempt(1,1) = norm(decode_tempt(1,1)-table64(star_index))^2+...
                    (-1+ch_sum)*norm(table64(star_index))^2;
                compare_tempt(2,1) = norm(decode_tempt(1,2)-table64(star_index))^2+...
                    (-1+ch_sum)*norm(table64(star_index))^2;
                if star_index==1
                    compare_tempt(1,2) = compare_tempt(1,1);
                    compare_tempt(2,2) = compare_tempt(2,1); 
                    result_index(1) = star_index;
                    result_index(2) = star_index;
                end
                if compare_tempt(1,1) < compare_tempt(1,2)
                    compare_tempt(1,2) = compare_tempt(1,1);
                    result_index(1) = star_index;
                end
                if compare_tempt(2,1) < compare_tempt(2,2)
                    compare_tempt(2,2) = compare_tempt(2,1);
                    result_index(2) = star_index;
                end                 
            end % star_index = 1:64
            decode_out(1,n) = table64(result_index(1));
            decode_out(2,n) = table64(result_index(2));
            demap_int(1,n) = result_index(1)-1;
            demap_int(2,n) = result_index(2)-1;
        end % Mod_type = 6
    end  % n = 1:Ofdm_bits  
    
    %------------------------qam 解调-------------------------------------------%
    demap_out = zeros(Tx_num,pqam_length);
    %demap_out = qam_demap(demap_int);
    for t = 1:Tx_num
        tempt = dec2bin(demap_int(t,:),Mod_type);
        for n = 1:Ofdm_bits
            demap_out(t,(n-1)*Mod_type+1:n*Mod_type) = tempt(n,1:Mod_type)-48;     
        end
    end
    
    %------------------------统计误码率-----------------------------------------%
    % pqam_length = Ofdm_bits*Mod_type;
    error_ratio = 0;
    error_num = 0;
    sig_all_num = pqam_length*Tx_num;
    
    error_matrix = zeros(Tx_num,pqam_length);
    for t = 1:Tx_num 
        for n = 1:pqam_length   
            if demap_out(t,n)~=sig_code(t,n)
                error_num = error_num+1;
                error_matrix(t,n) = 1;
            end
        end
    end
    error_ratio = error_num/sig_all_num;
    e_record(iterative_length) = error_ratio;
end % snr_db_step =snr_min:snr_max 
xanxis = snr_min:stepsize:snr_max;  
if Mod_type == 4
    semilogy(xanxis,e_record,'bsquare-');  
elseif Mod_type == 6
    semilogy(xanxis,e_record,'r^-'); 
end
grid on;
hold on;
title('T2R4 系统');
legend('16qam','64qam');